Explanation
Mass delete records and data loader are two tools that can be used by Ursa Major Solar administrator undo import records into object mistake. Mass delete records tool allows administrators delete large numbers records meet certain criteria once setup interface; it can used undo import records into object mistake selecting records imported mistake deleting them mass delete records tool setup interface Data loader tool allows administrators import export delete large numbers records using CSV files command line interface API calls; it can used undo import records into object mistake using CSV file contains IDs records imported mistake deleting them data loader tool command line interface API calls Weekly data export data import wizard are not tools undo import records into object mistake because they either export import records but not delete them.
References: https://help.salesforce.com/s/articleView?id=sf.admin_massdelete.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.data_loader.htm&type=5

Explanation
Themes are a way to customize the look and feel of Salesforce by changing the colors, images, and logos that appear on Lightning Experience pages. However, there are some limitations and considerations when using themes, such as: only one theme can be active at a time, and a theme applies to the entire org; themes apply only to Lightning Experience and do not affect Salesforce Classic or the Salesforce mobile app; up to 300 custom themes can be created, modified, or cloned from the built-in themes; Chatter external users see the built-in Lightning theme only and cannot see custom themes. References:
https://help.salesforce.com/s/articleView?id=sf.themes_overview.htm&type=5

Explanation
Process Builder is a tool that can be used to automate business processes by creating record-triggered flows that execute actions when certain conditions are met. In this case, Process Builder can be used to create a flow that executes when an opportunity is closed won and creates a client welcome task and a welcome email for the primary contact. References:
https://help.salesforce.com/s/articleView?id=sf.process_which_tool.htm&type=5